The present invention relates to devices, systems, and treatment methods directed at aligning and correcting orthodontic or dentofacial abnormalities, including both foundational correction (a treatment that changes the skeletal and/or dental tissues) and functional correction (a treatment that changes the soft tissues and/or tissue spaces).
More specifically, the present invention relates to devices, systems, and methods incorporating osteogenetic-orthodontic appliances. Osteogenetic-orthodontic appliances are specialized orthopedic and/or orthodontic appliances that signal the genome of the patient to remodel tissues and spaces.
In contrast, the prior art teaches that common orthodontic and dentofacial abnormalities are suitably corrected by using treatment methods and devices that apply continuous forces via brackets and wires (which translate to vectors that apply force to teeth).
Traditional orthodontic or dentofacial treatments that address orthopedic correction are known as Phase I treatments and are characterized, typically, as using bio-mechanical systems. Examples known in the art include Twin Block appliances. After Phase I treatments for orthopedic correction, using brackets bonded to teeth, Phase II is undertaken: Correcting, leveling, aligning, and rotation of the teeth is undertaken using wires of various shapes and sizes.
The present invention, along with traditional methods and devices, attempts to correct common orthodontic and craniofacial abnormalities, which are undesired for both esthetic and medical reasons. For example, in the craniofacial region, a well-balanced face is not only perceived as beautiful, but it is also free of health problems such as: dental malocclusions and tooth wear; facial underdevelopment (including facial asymmetry and craniofacial obesity); temporo-mandibular joint dysfunction (TMD), and upper airway difficulties, such as snoring, sleep disordered breathing, and obstructive sleep apnea (OSA). These conditions, whether diagnosed or covert, represent major issues in this field of work.
For example, traditional devices and treatments do not adequately address the underlying causes of poor tooth alignment. Poor tooth alignment is commonly accompanied by several other clinically-observable signs and symptoms, such as facial asymmetry, according to the patient's genome. One major issue not adequately addressed in the prior art teachings and traditional methods and devices is the irregular alignment of teeth as a result of development compensation. For example, malocclusion, an obvious sign of which is irregular teeth, belies a more serious issue, and may require correction and/or development of the bone constituting the jaws during comprehensive orthodontic care.
The current art does not fully treat the underlying cause by adequately interacting with or naturally-manipulating the genome because the traditional methods and devices do not recognize the importance of the gene-environmental interactions and, therefore, lack the structural elements necessary to properly signal the genes, which results in less than optimal corrections despite the temporo-spatial pattern or genetic template of facial development. Examples of common but detrimental environmental stimuli include myofunctional influences, such as bottle-feeding, a lack of breast-feeding, pacifier use, thumb-sucking, and other childhood habits including a soft diet of refined foods. Thus, dysfunctional features—such as adverse tongue posture, abnormal swallowing patterns, and lip activity—lead to further craniofacial consequences as the child matures (such as malocclusion). Yet, some of these consequences (such as obstructive sleep apnea) may not manifest until adulthood.
These consequences are the outcomes of gene-environmental factors that are thought to perturb the genetic craniofacial foundation encoded by genes, and include features such as a high-vaulted palate with maloccluded teeth, and functional features, such as a submandibular pannus (double chin). However, the complexity of these gene-environmental interactions leads to heterogeneity in terms of patient presentation. Thus, patients may present with a single feature, such as a malocclusion, TMD, snoring, wear facets on teeth, aged facial appearance, or any combination of the above, even though the underlying etiology is similar. For any foundational correction to remain stable, it must be co-provided with a functional correction.
More recently, biomechanical loading is thought to be an important regulator of osteogenesis, as bone formation occurs in response to its functional environment. Based on this information, biophysical techniques of osteo-stimulation have been successfully introduced into clinical practice.
These biophysical techniques include craniofacial distraction osteogenesis, and the application of ultrasound etc. to promote bone formation. As well, titanium implants are commonly used in orthopedics and dentistry. These implants integrate into the host's bone by a complex process known as osseo-integration. Data suggest that micromechanical forces may have anabolic effects on bone in-growth surrounding intra-osseous titanium implants.
For example, in one study micromechanical forces of 200 mN at 1 Hz were delivered axially to implants for 10 minutes per day for 12 consecutive days. The average bone volume near the mechanically loaded implants was significantly greater than the unloaded control side, and the average number of bone-producing osteoblast-like cells was significantly greater on the loaded side compared to the controls. There was also a significant increase in mineral apposition and bone-formation rate for the mechanically stressed implants compared to the controls. Therefore, modulation of bone in-growth can occur by in vivo micromechanical loading.
A considerable part of oral and maxillofacial surgery deals with bone healing. Recently, low-intensity ultrasound treatment has been shown to reduce the healing time of bone fractures. To observe the clinical effects of low intensity ultrasound after tooth extraction in patients, the sockets on one side were treated with low intensity ultrasound while the other side underwent no treatment. It was found that clinical use of low intensity ultrasound reduced post-operative pain and the incidence dry socket, and it also stimulated bone healing after extraction of mandibular third molar teeth. Therefore, the potential of ultrasound to stimulate maxillofacial bone healing may be of value in other orthopedic applications.
One study applied ultrasound to human gingival fibroblasts, mandibular osteoblasts, and monocytes. Ultrasound was found to induce cell proliferation in fibroblasts and osteoblasts by 35-50%. Collagen synthesis was also significantly enhanced (up to 110%) using a 45 kHz ultrasound device with intensities of 15 and 30 mW/cm2 (SA). In addition, angiogenesis-related cytokine production, such as IL-8, bFGF and VEGF were also significantly stimulated in osteoblasts. Therefore, therapeutic ultrasound induces in vitro cell proliferation, collagen production, bone formation, and angiogenesis.
Another known structure known in the prior art is sutures, which are fibrous connective tissue joints found between intramembranous craniofacial bones. They consist of multiple connective tissue cell lines, such as mesenchymal cells, fibroblasts, osteogenic cells, and osteoclasts. Sutures are organized with osteogenic cells at the periphery, producing a matrix that is mineralized during bone growth and development; with fibroblastic cells with their matrices in the center. Cyclic loading of these sutures may have clinical implications including acting as mechanical stimuli for modulating craniofacial growth and development in patients. One study demonstrated that in vivo mechanical forces regulate sutural growth responses in rats. In that study, cyclic compressive forces of 300 mN at 4 Hz were applied to the maxilla for 20 minutes per day over 5 consecutive days. Computerized analysis revealed that cyclic loading significantly increased the average widths of the sutures studied in comparison with matched controls, and the amount of osteoblast-occupied sutural bone surface was significantly greater in cyclically loaded sutures. These data demonstrate that cyclic forces are potent stimuli for modulating postnatal sutural development, potentially by stimulating both bone formation (osteogenesis) and remodeling (osteoclastogenesis).
In a similar study, static and cyclic forces with the same magnitude of 5N were applied to the maxilla in growing rabbits in vivo. Bone strain recordings showed that the waveforms of static force and 1 Hz cyclic force were expressed as corresponding static and cyclic sutural strain patterns. However, on application of repetitive 5N cyclic and static forces in vivo for 10 minutes per day over 12 days, cyclic loading induced significantly greater sutural widths than controls and static loading. Cell counting also revealed significantly more sutural cells on repetitive cyclic loading than sham control and static loading.
Fluorescent labeling of newly formed sutural bone demonstrated more osteogenesis on cyclic loading in comparison with sham control and static loading. Thus, the oscillatory component of cyclic force, or more precisely the resulting cyclic strain experienced in sutures, is a potent stimulus for sutural growth. The increased sutural growth by cyclic mechanical strain suggests that both microscale tension and compression induce anabolic sutural growth response. Therefore, mechanical forces readily modulate bone growth, and cyclic forces evoke greater anabolic responses of craniofacial sutures and cartilage.
In another study, the premaxillo-maxillary sutures of growing rabbits received in vivo exogenous static forces with peak magnitudes of 2N, or cyclic forces of 2N with frequencies of 0.2 Hz and 1 Hz. The static force and two cyclic forces did not evoke significant differences in the peak magnitude of static bone strain. However, cyclic forces at 0.2 Hz delivered to the premaxillo-maxillary suture for 10 minutes per day over 12 days (120 cycles per day) induced significantly more craniofacial growth, marked sutural separation, and islands of newly formed bone, in comparison with both sham controls and static force of matching peak magnitude.
This data demonstrates that application of brief doses of cyclic forces induces sutural osteogenesis more effectively than static forces with matching peak magnitude. Sutural growth is accelerated upon small doses of oscillatory strain (600 cycles delivered 10 minutes per day over 12 days), and both oscillatory tensile and compressive strains induce anabolic sutural responses beyond natural growth. Oscillatory strain likely modulates genes and transcription factors that activate cellular developmental pathways via mechanotransduction pathways. And, sutural growth is determined by hereditary and mechanical signals via gene-environmental interactions or epigenetics. Therefore, small doses of oscillatory mechanical stimuli have the potential to modulate sutural growth for therapeutic objectives.
The above data suggest that oro-facial sutures have capacities for mechanical deformation. The elastic properties of sutures are potentially useful for improving our understanding of their roles in facial development. Current data on suture mechanics suggest that mechanical forces regulate sutural growth by inducing sutural mechanical strain. Therefore, various orthopedic therapies, including orthodontic functional appliances, may induce sutural strain, leading to modification of natural sutural growth.
Additionally, for example, Singh G. D., Diaz, J., Busquets-Vaello, C., and Belfor, T. R. in “Soft tissue facial changes following treatment with a removable orthodontic appliance in adults,” Funct. Orthod., (2004) vol. 21 no. 3 at pp. 18-23 reported dental and facial changes in adults treated with a static removable orthodontic appliance (and as disclosed in United States Patent Application No. 2007/0264605 published on 15 Nov. 2007 and as disclosed in U.S. Pat. Nos. 7,314,372 issued on 1 Jan. 2008 and 7,357,635 issued on 15 Apr. 2008, the full disclosures of which are hereby incorporated by reference as if set out fully herein). The maxillary arch showed a 30-percent relative size increase in the mid-palatal region (corresponding to the mid-palatal suture) with shape changes consistent with improved dental alignment and maxillary expansion in the transverse direction. However, the treatment time was excessively long (up to 30 months in one case). Nevertheless, current orthodontic and dentofacial orthopedic therapies exclusively utilize static forces to change the shape of craniofacial bones via mechanically induced bone apposition and resorption, but cyclic forces capable of inducing different sutural strain wave forms may accelerate sutural anabolic or catabolic responses.
Recently, it was shown that low intensity pulsed ultrasound enhances jaw growth in primates when combined with a mandibular appliance, and that orthodontically induced root resorption can be repaired using ultrasound in humans.
Thus, there remains a need for improved treatment methods, systems, and devices that utilize therapy that harness the underlying developmental mechanisms—encoded at the level of the gene. Further, such improved treatment methods, devices, and systems should utilize the application of brief doses of cyclic forces to induce sutural osteogenesis. Additionally, there remains a need for a removable orthopedic-orthodontic appliance with cyclic functionality and a system and method to bioengineer vibrational orthopedic-orthodontic devices.
Further, teeth are adept at adapting to axial stimuli preferentially through physiologic mechanisms. These developmental mechanisms include active tooth eruption, passive tooth eruption; and the tooth support phenomenon. For example, when a deciduous tooth is lost, the permanent successor will typically actively erupt in an axial direction until it makes contact with an opposing tooth or teeth. Similarly, when a tooth is extracted, the opposing tooth can passively erupt until it meets some hindrance.
In the tooth support phenomenon, teeth undergo an initial elastic intrusion when an axial force is applied; and a further visco-elastic intrusion if the force is maintained, for example during mastication. When the axial force is removed, the tooth undergoes initial elastic extrusion and further visco-elastic extrusion (recovery) so that the tooth returns to its original position, in balance or in equilibrium with the opposing tooth/teeth. However, when an orthodontic device is applied to a tooth these natural mechanisms of homeostasis can be overpowered.
In contrast, during the development of the dentition, commonly referred to as tooth eruption, it is now thought that inherited genes are transcribed and expressed. The timing and orderly eruption of teeth is genetically-encoded in a developmental mechanism that is part of a systemic phenomenon called temporo-spatial patterning. In other words, specific teeth develop at specific sites at specific times. Thus, there is an innate, physiologic mechanism of tooth alignment that can be overpowered by biomechanical orthodontic therapy.
Moreover, current research in molecular genetics suggests that external stimuli can cause the expression of genes that are not normally expressed. Therefore, the application of appropriate external stimuli to teeth that have already completed their eruptive phase can cause these teeth to take up new positions in accord with the patient's genome as determined by temporo-spatial patterning, using the patient's own natural genome. Bearing in mind that teeth are adept at adapting to stimuli in the axial direction, the spring design described herein is orientated at an angle approximately parallel to the long axis of the palatal/lingual surface of the tooth, unlike all previous designs that contact the palatal/lingual surface of the tooth in the transverse plane.
Conventional orthodontic therapy is based on the premise that when a force is applied to a tooth, the tooth will move in response to the force. Thus, conventional fixed orthodontic approaches are primarily based upon the manipulation of teeth by exerting, controlling and maintaining forces, vectors and moments on teeth and/or roots. This torque control can be exerted on teeth either individually, segmentally or by the use of wires that engage the entire dental arch through the use of brackets.
In order to apply corrective forces, sophisticated systems of brackets and wires are commonly deployed. Brackets and/or bands of various designs are directly bonded to the surfaces of the teeth. The brackets have slots at various orientations that can engage wires. The wires are also of different materials, such as stainless steel and/or other alloys such as Nickel-Titanium; and of different cross-sectional shapes, such as round, square or rectangular; and of different sizes e.g. 0.016 inch round and 0.018 by 0.022 inch rectangular etc.
The wires are ligated to the brackets in various ways to permit low-friction, sliding mechanics, for example. Typically, the first phase of this biomechanical orthodontic correction is leveling using round wires, followed by more detailed tooth re-orientation using rectangular or square wires. Other corrections, such as space closure, are often accomplished by using elastics attached to the brackets or coil springs along the arch-wire to pull or push teeth into positions as determined by the orthodontic clinician.
From the patients' viewpoint, apart from esthetic considerations, one of the drawbacks of conventional fixed appliances is the trauma that the metallic orthodontic components and/or elastics may cause. The inside surface mucosa of the cheeks and lips, as well as the tongue, routinely contacts the metallic orthodontic components and/or elastics during swallowing, speech and mastication, which can cause cheek-biting, painful mouth ulcers, etc. In addition, inappropriate forces and moments that reach or exceed physiologic blood pressure during fixed orthodontic treatment can cause root resorption, by producing stresses in the periodontium. To avoid high pressures, the acting forces need to remain below about 0.5N. These levels of forces can be achieved by using Nickel-Titanium (NiTi) wires with a diameter of 0.012-inches, for example. The use of NiTi wires ensures an almost constant moment (torque) based on its stiffness, spring-back, shape memory, and elasticity. A superior NiTi alloy wire was developed by the Furukawa Electric Co., Ltd., Japan. This Japanese NiTi wire exhibits “super-elasticity” in that this particular wire delivers a constant force over an extended portion of its deactivation range. This Japanese NiTi alloy wire undergoes minimal permanent deformation during activation, and its stress remains nearly constant despite the change in strain within a specific range. This unique feature is called ‘super-elasticity’. Moreover, Titanium-Niobium-Aluminum (Ti—Nb—Al) springs generate lighter and more continuous forces. Thus, Ti—Nb—Al wire has superior mechanical properties for smooth, continuous tooth movement, and Ti—Nb—Al wire may be used as a nickel-free, shape-memory and super-elastic alloy wire for orthodontic tooth movement instead of Ni—Ti wire.
Similarly, NiTi coil springs, used with elastic chains, can generate nearly constant forces over a wide range of activation due to low load deflection. Reducing the load deflection rates of orthodontic springs is important, as it provides relative constancy of the moment-to-force ratio applied to the teeth with concomitant, predictable tooth movements. Lower load deflection rate springs increase patient comfort and reduce the number of office visits, while lowering potential tissue damage.
Using 0.016″×0.022″ NiTi and multi-stranded arch wires employed in a 0.018″ slot system, with power-hooks or up-righting springs, bodily tooth movements can be achieved. But, friction may increase if the up-righting torque is too strong and other unwanted side effects such as tooth extrusion, rotation and tipping can also occur. Therefore, the load-deflection rate of an orthodontic spring depends on the modulus of elasticity of the utilized alloy and the geometric configuration of the spring. Thus, it is usually preferable to choose springs with a low load-deflection rate of about 50 p/mm (50 kN/mm2). Nevertheless, it has been found that the force systems produced by straight wire and conventional up-righting springs can show severe extrusive force components, which may lead to occlusal trauma. Furthermore, intra-oral adjustment of up-righting springs is difficult because of high susceptibility to minor modifications of geometry.
Prior art had described the design and construction of the stainless steel flap springs utilized, including springs constructed of heat-treated alloy wire transversely orientated against the palatal/lingual surfaces of the pertinent teeth. Nevertheless, palatal finger springs; open springs; boxed springs; cranked palatal springs; re-curved springs, double cantilever or Z-springs, and T-springs etc. that are transversely orientated against the palatal/lingual or mesial/distal surfaces of the pertinent teeth are commonly found in the orthodontic literature as known by those skilled in the art. Indeed, the use of acrylic buttons attached to the palatal/lingual surfaces of pertinent teeth has been commonly deployed to prevent the transversely orientated spring from riding up the palatal/lingual tooth surface.
Thus, there remains a need for improved treatment methods, systems, and devices that utilize springs that harness the underlying developmental mechanisms—encoded at the level of the gene. Further, such improved treatment methods, devices, and systems should utilize cyclic intermittent forces to induce sutural osteogenesis. Additionally, there remains a need for a spring with cyclic functionality as a key component of a system and method to bioengineer vibrational orthopedic-orthodontic devices.